The Sd error means that the pressure switch has too much pressure on it during the drain and spin phase of the cycle which means there are too many suds in the washtub. This error is mostly caused by using too much liquid detergent. You should only be using about a tablespoon of detergent per load, if you are using more than that it's too much. At the time the error is shown the machine will try and fix the problem by filling it with some water and just allowing it to sit for 5 minutes to try and get the sud volume down. After this, it will spin and drain again. If the error continues to be an issue, then it could be a bad drain pump or water-level pressure switch. It could also be a stopped-up water-level pressure switch hose. Most commonly if you are certain this is not a suds issue the pump needs to be replaced. The drain pump can be ordered from the link below:
This Whirlpool Duet Washer SD error troubleshooting and repair information applies to model GHW9150PW0 and all the models listed under the related models section below.